To extent, QuickDraw was as (or even more) powerful in transparency
than Quartz is. CopyMask allowed per pixel per color component
alpha transparency!
And I can't think of a convenient way to do this in Quartz :). I
would think it's possible, but I'd have to poke around in a lot of
places.
CopyMask aside, plain primitives (rects, regions, etc) could also
been drawn with
blend mode - per color component alpha transparency.
From what I can tell however, that requires you to obliterate what
is in the destination to specify the alpha. Whereas with Quartz you
can specify the alpha directly (albeit not per-component).
Those both aside however, I think in general per-component alpha
processing might simply be better handled outside of either library.
Quartz isn't really designed for pixels, but for areas of color. Even
Images are handled conceptually as a grid of colored areas. When a
"color" is your basic unit of color, rather than color components, it
doesn't really make sense to break them into components to operate on
each separately.
- As we saw recently there are no easy ways (as of 10.4) to create
shapes (regions of new era) from polygons, paths and bitmaps.
Of course, unless you need to communicate with HIToolbox, your
welcome to use CGPathRefs for your clipping needs :).
- no easy way to mimic QD clipping handling with Quartz code (not
necessarily bad for Quartz, just a major difference).
I'm not certain what you mean by this. Quartz does have a different
clipping model, but you should be able to get similar, if not exactly
the same clips as you got with Quickdraw. Although you may have to
use a Mask to do so.
- there was no such a thing in QuickDraw, but I naively thought
it will be in Quartz, but it is not: ability to represent
arbitrary images (vector, bitmap, different formats, drawing proc)
by a "ref".
PDF can handle most of that. No drawing procs, sorry :). If you need
to interface with the toolbox, you can always convert a CGPDFPageRef
to a CGImageRef in about half a dozen lines of code - although I
agree that isn't convenient and you lose the advantages of PDFs.
--
Reality is what, when you stop believing in it, doesn't go away.
Failure is not an option. It is a privilege reserved for those who try.
David Duncan
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